Birdman cult

This is where those who were competing for the dubious pleasure of living in isolation for a year after having all your body hair removed, including eyelashes, set off to swim to the further away island. They were looking for the first egg of the sooty tern, and after they'd climbed down the cliff, swum 2k, climbed up onto the island and found the egg, they swum back with the egg in a headband without breaking it. I suspect they didn't know why they did it either.